Faculty Publications
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Item Enhanced Electrochemical Performance of Low-Content Graphene Oxide in Porous Co3O4 Microsheets for Dual Applications of Lithium-Ion Battery Anode and Lithium-Ion Capacitor(Springer, 2024) Lakshmi Sagar, G.; Brijesh, K.; Mukesh, P.; Amudha, A.; Bhat, K.S.; Nagaraja, H.S.The enhancement of electrochemical performance in lithium-ion battery (LIB) anode materials through nanostructures is of paramount importance, facilitated by the synergistic integration of these unique architectures with active materials, which increases the availability of active sites and decreases the diffusion path for lithium ions. In this investigation, we successfully synthesized cobalt oxide (Co3O4) microsheets composed of small nanoparticles (measuring 28–33 nm), employing a straightforward hydrothermal process followed by annealing. Furthermore, to enhance the composite’s ability to endure volume changes and increase its electrical conductivity, we created a Co3O4/reduced graphene oxide (rGO) composite embedding a judicious amount of graphene oxide (GO). This engineered composite exhibited remarkable specific discharge capacity of 1081 mAh g−1 at 100 mA g−1, a substantial improvement over the pristine material’s capacity of 718 mAh g−1. The composite demonstrated reduced irreversible capacity loss relative to the pristine counterpart and approached a reversible capacity of nearly 99%. Even after 400 cycles under the demanding conditions of high current density of 500 mA g−1, the composite managed to retain 81% of its initial capacity, underscoring its exceptional cycling stability. Moreover, the application of the Co3O4/rGO//carbon black (CB) assembly in lithium-ion capacitors (LIC) yielded notable energy density of 15.6 Wh kg−1 at elevated power density of 1007 W kg−1. These LIC devices demonstrated robust cyclic stability across extended cycles, sustaining 56% of their initial capacity after 2000 cycles while operating at a current density of 2 A g−1. Graphical Abstract: [Figure not available: see fulltext.]. © 2024, The Minerals, Metals & Materials Society.Item Synergistic boost in Fe3O4 anode performance for li-ion batteries via Zn and Cu double doping and multi-walled carbon nanotube composite integration(Elsevier B.V., 2024) Kumar, A.; Mukesh, P.; Lakshmi Sagar, G.; Hegde, A.; Nagaraja, H.S.In this study, a novel nanocomposite material comprising pure Fe3O4 (FO), doped Zn0.5Cu0.5Fe2O4-3 (ZCFO-3), and Zn0.5Cu0.5Fe2O4-3@ Multi-walled carbon nanotube (ZCFO-3@MWCNT) nanocomposite material is carefully prepared using a simple one-step hydrothermal process. Comprehensive surface and morphological analysis are conducted using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and High-resolution transmission electron microscopy (HRTEM), while compositional studies are investigated through Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrochemical performance is fully analyzed through Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), rate capability tests, discharge/charge capacity, and cyclic stability evaluations. Among these three nanomaterials, ZCFO-3@MWCNT nanocomposite at 100 mA g−1 current density reveals the best performance, with a discharge capacity of 1974 mAh g–1, ZCFO-3 and FO reveal 1340 mAh g–1 and 1317 mAh g–1 respectively. After 800 cycles at 500 mA g−1 current density, ZCFO-3@MWCNT stays strong with a discharge capacity of 646 mAh g–1, while ZCFO-3 manages only 362 mAh g–1 and FO only 111 mAh g–1. After 1200 cycles at 500 mA g−1, the nanocomposite still delivers 518 mAh g–1. This study suggests that ZCFO-3@MWCNT could be a promising anode material for lithium-ion batteries. © 2024 Elsevier B.V.Item Reinforcing NiO microsphere structural stability via amorphous carbon sheets obtained from waste milk for lithium-ion capacitor application(Springer Science and Business Media B.V., 2025) Lakshmi Sagar, G.; Brijesh, K.; Mukesh, P.; Hegde, A.P.; Kumar, A.; Paliwal, A.; Bhat, K.S.; Nagaraja, H.S.In the pursuit of sustainable chemistry and environmentally friendly energy storage, the study addressed the limitations of nickel oxide utilized as the active material for the anode in lithium-ion capacitors. Despite its abundance and favorable environmental properties, NiO suffered from significant volumetric expansion and slow electrochemical kinetics compared to carbon materials. To overcome these issues, amorphous carbon was extracted from spoiled waste milk through a simple combustion process, effectively converting biomass waste into renewable resources. The engineered NiO/amorphous carbon composite, synthesized through hydrothermal and annealing processes, mitigated the limitations of NiO. Field Emission Scanning Electron Microscopy confirmed the deposition of amorphous carbon sheets encasing NiO microspheres, which preserved structural integrity during electrochemical cycling. The amorphous carbon acted as a stabilizing matrix, encapsulating NiO microspheres to mitigate volumetric expansion and enhance lithium-ion transport kinetics. Electrochemical tests demonstrated a specific discharge capacity of 1230 mAh g?1 at a current density of 100 mA g?1, retaining 401 mAh g?1 after 1000 cycles at 1 A g?1, nearly doubling the retention performance of pristine NiO. Furthermore, the NiO/AC//AC lithium-ion capacitor achieved an energy density of 25.4 Wh kg?1 at a power density of 1991 W kg?1, maintaining 96% capacity after 3500 cycles. This study highlighted the potential of waste-derived carbon in developing high-performance, sustainable energy storage systems. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.